Cylindrical test gauge



Patented Jan. 8, 1946 STATES PATENT oFFlcE- J ames G'. Sisson, lAjthoLrMass.; assi`gnor"t"The" L: S.` Starrett' Company, .AthoL Mass., a corpo-v ration of iMassachusetts Application March-.20, 19in-sentirne527,263

@claim-s. (o1. :i3- 178) The present` invention.: involves improvements in. gauges for' testingI cylindrical surfaces.. Surfaces,` offwhich` ballabearing ,-races, connecting rod bearings.. orfthe-rlike,xare Ygood examples. of vparts which, inf.. manufacture; or. by -v use, depart' from their-intended'. radi-usfof design, andl .the demand isffor an' vaccurate land. i easily operated. gauge lby which` the variationszirrA such'. surfaces can be readilymeasuredisolthat, forexample, theamounft of 'enlargement Ain .re-boring orfo 're-'lining may bef-readily,4 determined'.

The. use I off a',Y gaugefon; similaril principlsfi for testing.; engine.- cylinders; -as'ziniLetters Patent 'to Simpson N o. 1,847,906,\March 1, .1932,r hasfdem; onstrated` the.y I eiliciencyf4 of fthe threeiepoint-basis of :suchf gauginggwhichfzgoesback? to July 1,1 1919, as is shown in Letters Patent to BellardiNo. 1,308,3245.

The present gauge is a further response to the demand indicated in Letters Patent to Blomstrom No. 2,087,896. This gauge was quite successful but lacked the handiness so necessary to the mechanics efficiency in accurately and rapidly testing different kinds of parts or work where close tolerances are essential.

A gauge in accordance with my invention comprises a base having a longitudinal slot therethrough which supports a plunger-operated indicator having a finger extending through the slot adjacent one of its ends. A slide supporting a contact and a pair of laterally spaced springpressed plungers is carried by the base to move from a position adjacent the contact finger towards a position adjacent the other end of the base, and I provide means to clamp the slide to the base so that the surface contacting means carried by the slide and the indicator operating finger establish points for engagement with diametrically opposite Zones of cylindrical surfaces. By this construction I am able to provide a gauge inexpensive to manufacture, Well adapted for speedy and accurate use in determining the cylindricities of a wide range of surfaces. i

As illustrative embodiments of the present invention, the accompanying drawing shows a practical example of a gauge to measure the out-ofroundness of inside cylindrical surfaces.

In the drawing:

Fig. 1 is a plan View of a gauge in accordance with my present invention.

Fig. 2 is a side elevation of the same.

Fig. 3 shows a bottom view of the gauge.

Fig. 4 is a sectionI on the line 4-4, of Fig. l, looking in the direction of the arrows.

Fig. 5 is a section on the line 5-5, of Fig. 1, and

. reference tolth'e dial |55l The-dial indicator shown has a bezel4r lll'bylwhich theV zero marking of the dial |5 may-bey adjusted'w-hen the .set screw I8; is released.A

Inf? accordance with myr invention, I attach-1 -to thec plungerl' I3- aiE contactl finger |911 fitting`lthe slotl |I?fandextending'ithrough it adjacent onev end thereof;4

At20`l1-h`ave indicated alslide milled-las at 2| to receive .thebase I {Dto-.be slidablyfgu'ided :thereby. The slide 20 has an aperture 22 to receive the bolt 23, the flattened head 24 of which is shaped to flt the slideway established by the shouldered slot so that the head 24 is iiush with the upper surface of the base I0 and is held against rotation. A knurled lock nut 25 is formed to receive a coiled spring 26 which rests against the slide 20. By this construction, the slide may be freely moved from a position adjacent the nnger I9 to the opposite end of the slot I I and locked in any desired position by tightening the lock nut 25.

Preferably I form the slide 20 to establish laterally of the aperture 22 a pair of mounts 21 each having a longitudinal bore 28 of reduced diameter adjacent its rear end to define a shoulder 29. Each of the bores 28 receives a contact plunger 30 the diameter of which is reduced as at 3| and 32 to establish shoulders 33 and 34. A spring 35 is seated against each of the shoulders 29 and 33 so that the tContact plungers 30 are always urged towards the surface to be tested.

The contact plungers 30 are interconnected by a strap 36 seated against the shoulders 34 by screws 31 threaded into the rear ends of the contact plungers. Between the spring-pressed contact plungersl I provide a short contact pin 38 threaded into the slide 20.-

By this construction the finger I9 and the contact 38 are held in a true diametrical position to permit the cylindricity of an object to be quickly and accurately tested. In use, as for example, in testing the cylindricity of connecting rod bearings or bushings, the work is applied to the feeler points'of the gauge (finger I9 and contact plungers 30) which have been roughly positioned for the easily operated gauge adapted ioruse in testing cylindricity. Y ,1 v Y* Various designs or combinations may and will contact depending from said slide and disposed to occupy a position substantially parallel to said contact finger, and a pair of spaced spring-pressed plungers extending forwardly of said slide on either side of said second contact to hold the gauge diametrically of theqylindrical surface to V be tested.

doubtless be made, without departing from the Y spirit of the present improvements, to meet newY needs and requirements as they arise. Y

y What I therefore claim and desire to secure by Letters Patent is: 1. A gauge comprising a basehaving parallel g sides and a shouldered slot, an indicator mounted o on said base and having an operating plunger, a 1vr 3. A gauge comprising a lbase, a i'irst surfaceengaging vcontact comprising a 'depending contact ynger and an indicator having an operat- -ing plunger from which said iinger depends, a

, second surface-engaging contact supportedY by contact finger carried by said plunger and exl tending through said slot adjacent one of the ends thereof, a slide formed to be slidablv guided by said base, said slide having an aperture therethrough, a headed bolt slidably seatedand supported in said shouldered slot andY extending through the aperture in said slide, a locking. cap

threaded on said bolt, andaspring housed within and seated by saidvcapagainst said slide. a

. contact member carried by said slide, and a pair of spaced spring-pressed plungers carried by said slide to position said contact nger and said contact member VdiametricallT with respect to the cylindrical surfacesto b'e tested.

2. A gauge comprising a base having a slot-1an erate said, indicator, a contact yiinger Y depending from said plunger and extending through said l slot adjacent one end thereof, a slide adjustable 4along said base 'relative to^said contactk finger, meansto lock said slide to said base, a second indicator mounted on said base, a plungerv toopsadrbase and comprising a'sli'de adjustable along said base, a contact member depending from said slide and disposed to occupy a position substantially parallel to said contact finger and a pair of spaced spring-pressed plungers extending for-` f Wardly of said slide on either side of said contact member, one of said sur jee-engaging con: tacts being adjustable relativ'e'to the other Vfor cylindrical surfaces of different diameters.

4. Agauge comprising a base having a slot, an

indicator mounted onvsaid base and having an op'.

erating plungen'a -contact nger'carried by said plunger and extendingthrough said slot adjacent one end thereof, a slideradjustable' along said base relative to said contact finger and having a pair of shouldered bores, means to lock said :slide to said base, a contact member carried by said slide, a pair of spaced spring-Dressed contactplungers carried by said slide at either side of said contact member and each formedpwith a pair of shoulders, a spring seated between oneY of said lastnamed shouldersand the shoulders in the bore, and a connecting link seated on thei other shouldersY of said spring-pressed plungersrand locked thereto.v j Y V JAMES G. SISSON. 

